THE HEALTHY SKEPTIC

Allergen Block: invisible shield or invisible results?

Allergists are dubious that the gel prevents airborne allergens from reaching sufferers' nostrils.

As long as cats keep shedding and trees keep trying to make more trees, a lot of allergy sufferers are going to be looking for relief. They might take medications to reduce their symptoms, or they might try to stay away from cat dander, pollen and other nuisances.

But what if allergy sufferers could stop those airborne offenders before they had a chance to cause trouble? That's the premise behind Chloraseptic Allergen Block and Little Allergies Allergen Block for children, gels that supposedly trap allergens right under a person's nose.

Allergen Block and Little Allergies Allergen Block -- both produced by Prestige Brands Inc. -- are identical gels in different packages. Each product consists of petrolatum (petroleum jelly), glycerin and so-called cationic molecules that the company declines to identify.

Users are instructed to apply a small dab of the gel underneath the nose and around the edge of the nostrils every four to six hours or as needed. According to the Allergen Block website, the gel works on the principle that opposites attract. Those cationic molecules are said to create a positive charge that pulls negatively charged allergens into the gel, where they presumably get stuck like little mammals in a tar pit.

Because the gel doesn't contain active drugs and isn't used internally, it isn't considered to be a medication. The Food and Drug Administration has officially approved it as a "device." The FDA approval process for devices is much less rigorous than it is for drugs. Prestige Brands didn't have to prove that the Allergen Block is effective. It merely had to make a case that it was "substantially equivalent" to other products already on the market.

Sold at major drug stores, a 0.1 ounce tube of either type of Allergen Block costs about $14. When used as directed, each tube is enough for about 150 applications.

The claims

The Allergen Block website claims that the gel protects against ragweed, pollen, dust mites, pet dander and house dust. It also claims that it helps prevent sneezing, nasal congestion, itchy nose and runny nose.

A television ad for Allergen Block says it "creates an invisible shield that helps block airborne allergens before they travel up your nose."

In a phone interview, the inventor of Allergen Block, Ashok Wahi, an engineer living in New Jersey, said that the gel dramatically relieved his daughter's cat allergies. "It worked for my daughter and a million other users," he said.

The bottom line

As appealing as an allergen blocker may be, there's not much chance that smearing gel beneath the nose will prevent a single sneeze, according to Dr. Richard Greene, an allergist with a private practice in Reading, Pa., and a fellow of the American Academy of Allergy, Asthma and Immunology. "I can't in my wildest imagination see how this would work," he said. Even if the gel did somehow attract allergens -- an open question in his mind -- he believes the force of a gentle inhale would still pull in plenty of dust, pollen and whatever else was in the air. "You would have to literally put a filter in your nose to really block allergens," Greene said.

Greene's comments fulfilled the prophecy of Dr. Paul Ratner, a San Antonio-based allergist who assisted in the development of Allergen Block. "Allergists are going to say that this is preposterous," Ratner said. Prestige Brands conducted two small unpublished studies of the gel, but Ratner said the company hasn't provided the type of evidence that would sway experts. "I understand their skepticism, I really do."

For starters, Ratner acknowledges that there's not much scientific proof that allergens have a negative charge. (In fact, a study by English researchers in the late 1990s found that dust mite allergens tend to be positively charged.) More importantly, there's no solid evidence that people using the gel breathe in fewer allergens.

According to Ratner, Prestige Brands has considered testing the gels with an artificial nose in a wind tunnel full of pollen. Such a test would show definitely whether or not the gel actually keeps allergens out of the nose -- at least the artificial type of nose.

Ratner -- who owns a small amount of stock in Wahi's company, Trutek, which licensed Allergen Block to Prestige Brands -- said that since Allergen Block is inexpensive and doesn't cause side effects, many allergy sufferers might find it worth a try.

Dr. Marc Riedl, an assistant professor of clinical immunology and allergy at UCLA Medical Center, said he "doesn't see how this product could do any harm." But based on the evidence, even at $14 for 150 applications, Allergen Block doesn't seem like a smart investment to him. "The unfortunate thing is that if enough people are willing to try this, the company will make a lot of money without really helping anyone," he said.